As high-voltage and high-energy density batteries, for example, Li ion batteries are known. The Li ion battery is a cation-based battery utilizing Li ions as the carrier. Meanwhile, as anion-based batteries, fluoride ion batteries utilizing fluoride ions as the carrier are known.
For example, Patent Literature 1 discloses that CeFx is used as a cathode active material in a fluoride ion battery. Also, Patent Literature 2 discloses that CuF, CuF2, PbF2, and PbF4 are used as a cathode active material in a fluoride ion battery. Also, Patent Literature 3 discloses that a metal fluoride represented by composition formula: MFx (provided that, M represents a metal, and X represents the valence of the metal M), as a cathode active material in a fluoride ion battery. Also, Non-Patent Literature 1 discloses that CuF2 is used as a cathode active material in a fluoride ion battery.